Long-life carbon electrodes for weather tester and the like

ABSTRACT

Improved carbon electrodes for use in a carbon arc lamp are disclosed. The improved electrodes, which are utilized in pairs, have a diameter ratio of the upper to lower electrodes within the range of 1.4 - 1.6 : 1. The electrodes consist of a core section, a carbonaceous portion surrounding the core section and a layer of material covering the carbonaceous portion. The ratio of the sectional area of the carbonaceous portion to that of the core portion in the upper carbon electrode should be within the range of 9 - 14 : 1 with the ratio in the lower carbon electrodes being within the range of 5 - 9 : 1. Electrodes produced according to the subject invention provide spectroscopically stabilized light at a discharge voltage and current of 50 volts and 60 amps., and have improved long life performance.

United States Patent 1 1 Suga 1 1 LONG-LIFE CARBON ELECTRODES FOR WEATHER TESTER AND THE LIKE Shigeru Suga, Yoyogi 5-20-2, Shibuya-Ku, Tokyo. Japan 22 Filed: on. 7, 1974 211 Appl. N0i;s12,ss2

{76] Inventor:

Primary E.ruminvrA1fred E. Smith Axxixrun! 1i.\'amim'rWm. H Punter Attorney, Agent, or Firmwenderoth Lind & Ponack 1 Aug. 19, 1975 [57 1 ABSTRACT lmproved carbon electrodes for use in a carbon arc lamp are disclosed. The improved electrodes. which are utilized in pairs, have a diameter ratio of the upper to lower electrodes within the range of 1.4 1.6 1. The electrodes consist of a core section. a carbonaceous portion surrounding the core section and a layer of material covering the carbonaceous portion. The ratio of the sectional area of the carbonaceous portion to that of the core portion in the upper carbon electrode should be within the range of 9 l4 l with the ratio in the lower carbon electrodes being within the range of 5 9 l. Electrodes produced according to the subject invention provide spectroscopically stabilized light at a discharge voltage and current of 5() volts and 60 amps. and have improved long, life performance.

1 Claim, 9 Drawing Figures LONG-LIFE CARBON ELECTRODES FOR WEATHER TESTER AND THE LIKE BACKGROUND OF THE INVENTION l. Field of the Invention The subject invention relates to improvement in the carbon electrodes which are used in carbon arc lamps for weather testers or climatic testing machines and the like.

2. Description of the Prior Art Arc lamps for weather testers and the like typically comprise four sets of vertically arranged carbon electrodes which are energized by. for instance, a servo motor at a voltage and current of 50 volts and 60 ampsrespectively. to light the lamp. A specimen being tested is placed around the arc lamp for testing. Each of the carbon electrodes include a core portion made of a luminous material such as cerium fluoride and has a gear-shape configuration with the number of teeth ranging from 6 to 12. A carbonaceous portion surrounds the core portion of the carbon electrode and a layer of copper or the like coats the carbonaceous portion,

Commonly used carbon electrodes have lengths of approximately 305 mm. with upper electrode diameters of 23 mm. and lower electrode diameters of 13 mm. An assembly of four sets of upper and lower carbon electrodes. when continuously activated, has a functional life of approximately 20 to 22 hours.

The life of the carbon electrode can be doubled by doubling its length. This, however, necessitates a corresponding enlargement of the are lamp control mechanism. lamp housing and other elements and creates problems of economy. Another known manner of prolonging the life of the carbon electrode is to increase the diameter thereof. However. if the carbon volume is doubled. that is. if the diameter is increased l.4l times by. for instance. increasing the outer diameter of the upper carbon electrode from 23 mm. to 32.5 mm. and the diameter of the lower carbon electrode from l3 mm. to 18 mm., the life of the electrode is only increased l.6 times. This is partially attributable to the fact that the relation between the sectional area of the core portion and that of the carbonaceous portion there-around is not suited to the discharge pattern of the electrode.

SUMMARY OF THE INVENTION It is a primary object of the subject invention to produce improved carbon electrodes for use in a carbon arc lamp having a longer useful life than heretofore obtainable with conventional carbon electrodes.

It is a further object of the subject invention to pro vide improved carbon electrodes for use in a carbon arc lamp having spectroscopically stabilized light at a discharge voltage and current which is comparable to that normally found in weather testers and the like.

The above objects are achieved in accordance with the present invention by the provision of upper and lower electrodes wherein the diameter ratio of the upper and lower electrodes is within the range of L4 [.6 1.0. Moreover. the ratio of the sectional area of the carbonaceous portion to that of the core portion in the upper carbon electrodes should be within the range of 9 l4 l with the ratio in the lower carbon electrodes within the range of 9 l. A carbon arc lamp having electrodes produced in accordance with the above noted specification is capable of continuously producing spectroscopically stabilized light for a time period in excess of 24 hours. In addition. upper and lower carbon electrodes produced in accordance with the subject invention also have similar ratios of combustion to length.

BRIEF DESCRIPTION OF THE DRAWINGS The features of the invention will be described in more detail below with reference to the accompanying drawings wherein:

FIG. I is a partial prospective view of an electrode produced in accordance with the present invention;

FIG. 2 is a longitudinal sectional view of FIG. 1;

FIG. 3 is a cross-sectional view of an upper carbon electrode produced in accordance with the subject invention;

FIG. 4 is a cross-sectional view of a lower carbon electrode produced in accordance with the subject invention;

FIGS. 5, 6 and 7 are sectional views showing discharge patterns between upper and lower electrodes having various sectional configurations;

FIG. 8 is a chart depicting the operability of the device of FIG. 7; and

FIG. 9 is a chart depicting the operation of the electrode assembly shown in FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings. reference numeral 1 indicates the copper coating or layer which covers the carbon electrodes. The carbonaceous portion is indicated by reference numeral 2 and the core portion, filled with a luminous material stabilizer is indicated by reference numeral 3. This 3-layered configuration is known in the art. However, the specific ratios of area which will be disclosed hereinbelow have neither been suggested nor disclosed in the prior art and produce new, useful and unobvious results as compared with the results obtained by conventional electrodes.

FIGS. 5. 6 and 7 disclose electrode combinations of upper electrodes respectively. having a large core portion. a medium core portion, and a small core portion while utilizing identical lower electrodes. When are lamps using the respective combination of upper and lower electrodes are lighted, the discharge pattern shown in FIGS. 5 through 7 are produced. If a large core is used. a large discharge are is produced, which causes rapid wear of the electrode since the carbon portion is thin as may be seen in FIG. 5. On the other hand, if the core is small the discharge are is produced at the carbon portion, off the core, and the are moves unstably, as shown in FIGS. 6 and 9. When the core is medium in size (having a matched diameter). a correct arc is produced between the upper and lower carbon electrodes and very stable light is produced. This is particularly shown in FIGS. 7 and 8.

In view of the above noted data. the carbon portion must be increased to prolong the life of the electrode and the core size must be slightly enlarged to stabilize the emitted light. This may be accomplished by designing electrodes having specific ratios of core portion sectional areas to carbonaceous portion sectional ar- Applicant has determined that the ratio of the carbon portion sectional area and the core portion sectional area should preferably be within the range of 9 l4 l 'for the upper carbon electrode and the lower carbon electrodes should have a corresponding ratio of 5 9 l Furthermore. the ratio of the outer diameter of the upper carbon electrode to the outer diameter of the lower carbon electrode should be within the range 1.4 1.6 l to produce optimum results.

The following Table presents a comparison of struc ture and performance of typical prior art carbon electrodes with carbon electrodes produced according to the teachings of the present invention.

Carbon electrodes It will be apparent to those skilled in the art that many modifications of the above specifically described apparatus may be made without departing from the spirit and scope of the present invention.

I claim:

1. in a carbon arc lamp for use in weather testers and the like and including pairs of upper and lower electrodes. each of said upper and lower electrodes comprised of a core portion formed of a luminous material. a carbonaceous portion surrounding said core portion and a layer of copper or like material positioned over of prior art of present invention Upper Lower Upper bower Diameter (elec- 23 mm [3 mm 35 mm 23 mm trodes) Ratio (upper/ L77 L52 lower) Coaw (sectional 70.8 mm 23.7 mm 70.8 mm 58.6 mm area) Carbonaceous portion (sectional 344 mm I09 mm 89] mm 356 mm area) Ratio of sectional area 4.85 4.59 12.6 6.0

carbon/core about 0,1 mm thick The efficacy of the subject invention has thus been confirmed by experimental data. In a preferred embodiment, it was established that long life and most stable light can be obtained by using upper carbon electrodes having a diameter of 35 mm. and in which the sectional area ratio of the carbonaceous portion to the core portion is approximately 12 l and in which the lower carbon electrodes have a diameter of 23 mm. and a corresponding ratio of 6 I.

As noted earlier, it is quite desirable that carbon arc lamps used for weather testers and the like have a long continuous lighting capability. The subject invention has succeeded in extending the functional capabilities of carbon electrodes from the conventional to 22 hours to more than 40 hours. Not only does this result in great economy. but it also permits operation of test ing devices during holiday and the like when maintenance personnel are otherwise unavailable.

said carbonaceous portion, the improvement which comprises the diameter ratio of the upper to the lower electrodes being within the range of 1.4 L6 L0. and the ratio of the sectional area of the carbonaceous portion to that of the core portion in the upper carbon electrodes being within the range of 9 l4 l with the ratio in the lower carbon electrodes being within the range of 5 9 l, whereby an improved carbon electrode combination is provided in which the upper and lower carbon electrodes have the same rate of combustion to length and can provide spectroscopically stabilized light at a discharge voltage and current of 50 V and A respectively, normally used in weather testers. and which also has improved long-life performance in excess of 24 hours of continuous lighting. 

1. IN A CARBON ACR LAMP FOR USE IN WEATHER TESTERS AND THE LIKE AND INCLUDING PAIRS OF UPPER AND LOWER ELECTRODES, EACH OF SAID UPPER AND LOWER ELECTRODES COMPRISED OF A CORE PORTION FORMED OF A LUMINOUS MATERIAL, A CARBONACEOUS PORTION SURROUNDING SAID CORE PORTION AND A LAYER OF COPPER OR LIKE MATERIAL POSITIONED OVER SAID CARBONACEOUS PORTION, THE IMPROVEMENT WHICH COMPRISES THE DIAMETER RATIO OF THE UPPER TO THE LOWER ELECTRODES BEING WITHIN THE RANGE OF 1.4 - 1.6 : 1.0, AND THE RATIO OF THE SECTIONAL AREA OF THE CARBONACEOUS PORTION TO THAT OF THE CORE PORTION IN THE UPPER CARBON ELECTRODES BEING WITHIN THE RANGE OF 9 - 14 : 1 WITH THE RATIO IN THE LOWER CARBON ELECTRODES BEING WITHIN THE ANGE OF 5 - 9 : 1, WHEREBY AN IMPROVED CARBON ELECTRODE COMBINATION IS PROVIDED IN WHICH THE UPPER AND LOWER CARBON ELECTRODES HAVE THE SAME RATE OF COMBUSTION TO LENGTH AND CAN PROVIDE SPECTROSCOPICALLY STABILIZED LIGHT AT A DISCHARGE VOLTAGE AND CURRENT OF 50 V AND 60A RESPCTIVELY, NORMALLY USED IN WEATHER TESTES, AND WHICH ALSO HAS IMPROVED LONG-LIFE PERFORMANCE IN EXCESS OF 24 HOURS OF CONTINUOUS LIGHTING. 